by Kevin Johnson, USA TODAY

by Kevin Johnson, USA TODAY

WASHINGTON - National Security Agency Director Keith Alexander told a House committee Tuesday that more than 50 terror threats throughout the world have been disrupted with the assistance of two secret surveillance programs that were recently disclosed by former defense contractor Edward Snowden.

More than 10 of the plots targeted the U.S. homeland, Alexander told the House Intelligence Committee, including a plot to attack the New York Stock Exchange.

"I would much rather be here today debating this,'' Alexander told lawmakers, referring to the programs' value, "than explaining why we were unable to prevent another 9/11'' attack.

At the rare open committee hearing, Alexander and Deputy Attorney General Jim Cole told lawmakers that both surveillance operations - a domestic telephone tracking system that collects records of millions of Americans and an Internet monitoring program targeting non-citizens outside the U.S. - have been subject to rigorous oversight to guard against privacy abuses.

"This isn't some rogue operation that some guys at the NSA are operating,'' said Alexander, also an Army general.

Deputy FBI Director Sean Joyce described another threat Tuesday that was neutralized by the surveillance programs: Investigators used the phone tracking system to identify an operative in San Diego who was providing support to terrorists in Somalia.

Joyce also referred to two disrupted plots that were disclosed last week as having been thwarted by the surveillance operations, including a 2009 plan to bomb the New York subway system.

In that case, authorities used its Internet monitoring program to identify overseas communications involving Najibullah Zazi in Colorado, who was later convicted in connection with the subway attack plan.

"This is not a program that is off the books,'' Cole said, outlining the executive, legislative and judicial controls attached to both surveillance operations.

In the plot against the stock exchange, Joyce said investigators identified a former New York accountant working with contacts in Yemen who were in the early stages of planning an assault against the exchange.

Joyce did not name the man. In court documents, however, he is identified as Sabirhan Hasanoff, 37, who pleaded guilty last year to providing support to al-Qaeda. Hasanoff was not charged in a plot against the stock exchange, but prosecutors, while arguing for a harsh prison sentence, alleged in court documents that Hasanoff "cased the New York Stock Exchange'' at the direction of a senior terror leader in Yemen.

Prosecutors allege that Hasanoff was working with two operatives in Yemen--known by their aliases as "Suffian'' and "The Doctor.''

Hasanoff, according to the prosecutors, prepared a "rudimentary'' surveillance report on the alleged target and transmitted it back to the Yemen operatives.

Citing the stock exchange surveillance, the prosecutors argued that Hasanoff is a "terrible candidate for this court's mercy.''

Hasanoff's attorney was not immediately available for comment.

Lawmakers raised few questions about the intelligence officials' authority to conduct the operations, despite the heated national privacy debate that was prompted by Snowden's disclosures.

Rep. Mike Rogers, R-Mich., the panel's chairman, said the programs were "designed'' to protect Americans.

"Trust can wane when faced with so many inaccuracies,'' Rogers said, noting the "mis-perceptions'' about the surveillance operations caused by "wrong'' news reports.

Alexander said intelligence officials have "significant concerns'' about the access to such sensitive information. He said about 1,000 so-called system administrators have access similar to Snowden. And a majority, like Snowden, are contractors.

"We do have significant concerns in this area and it is something we need to look at,'' Alexander said.

Joyce said a criminal investigation into Snowden's disclosures is continuing. Asked what he expected to result from that inquiry, Joyce offered a blunt assessment.